linux-kernel - Re: [PATCH] x86: put initial_pg

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Message-ID: <49AACEB3.5050206@kernel.org>
Date:	Sun, 01 Mar 2009 10:06:43 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: Re: [PATCH] x86: put initial_pg_tables into bss -v2

H. Peter Anvin wrote:
> Yinghai Lu wrote:
>> Impact: cleanup
>>
>> Don't use ram after _end blindly for pagetables.
>> put those pg table into bss
>>
>> also remove init_pg_tables_start/end tricks all around
>>
>> v2: keep initial page table up to 512M only.
...

> 
> No, this is garbage.  If you're insisting on getting rid of the brk-like
> allocation patterns, then you have to get an alternative dynamic
> allocator available to the pre-paging code.  Now, there is no reason we
> couldn't execute C code before enabling paging, although the code would
> either have to be PIC or linked at the physical address.

you can use find_e820_area()/reserve_early() pair to find right position for that.

YH
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